I've done at least three different sets of Amazon phone interviews over the years and to my surprise, I actually made it through the phone screen process on this last try and made it to the doors of Amazon.com in downtown Seattle.
Now about the actual interview process: I did two phone interviews over a 2 - 3 week period, and then another 2 - 3 weeks to get around to the actual in-person interview (in other words, Amazon wasn't in any major hurry). I felt the phone interviews (talking on the phone while furiously typing into a collabedit web site) were far more stressful than the on-site interviews, although all of the interviews were quite intense, technically. The recruiting coordinator is not the same person as the H.R. person who you'll meet during the interview (although in my case, I got to meet both). The H.R. lady was as cold and generic as they come, informing the candidates up front that Amazon is a "no feedback" company (which -- to their credit -- is a lot more honest and open about not providing constructive comments, versus most every other employer who just will say "we've decided to go forward with other candidates" and leave it at that).
My interview day was scheduled to go from 9:30 until about 1:30 p.m. and they attempt to keep to that schedule and they won't do "bonus" (additional) interviews tacked on at the end of an exhausting day like Microsoft will do. In my case, I did at least three technical rounds with at least two of them being "tag team" interviews (two interviewers quizzing me at the same time).
The first set was a project manager with a senior software engineer mostly listening in. Their question consisted of "design a restaurant reservation system".
The second set of tag team interviews was a senior software engineer (probably the one I would have worked closest with) along with a teenage software intern along to watch the ritual candidate slaughter. In this case, because this particular senior engineer was closest to my background and my specialty, I felt like I was able to relate to him best and explain myself properly, as I worked up and white-boarded out a nice architecture-specific feature-enhancement for the product I think they had me in mind to work on.
The third interview was a manager who was unexpectedly pulled into speaking with me when my originally arranged interviewer got held back on some unknown something. He made sour faces at my dense resume as he paged through it, since he had no time to prepare for speaking with me, he didn't ask me any memorable questions about my background, and I felt like this conversation was almost as uncomfortable as….
…. the lunch interview with the hiring manager. A week prior to my interview day, the recruiting coordinator e-mailed a menu and asked me to make a selection for a box lunch. I chose what I felt would be a safe choice (salad, so as to not be tired from a full stomach), but in retrospect, I probably should have chosen nothing at all. Because when I wanted to talk with the hiring manager & find out more about the big picture of the business, either he was eating or I was eating something, and one of us had our mouths full and it just wasn't the engaging conversation I wanted to have with the person who was going to potentially sign the dotted line to me getting hired. What would have been preferable would be for me to go to lunch on my own (just to collect my thoughts or regroup) or go to lunch with somebody -- or some host -- who has no up or down vote at all in the process (which is what Google does with their candidates).
The last technical round I had with was an analytics guy, sent in to test my general data structures and algorithms background. He had me drawing trees on the white board and then describing rules to determine whether a flipped tree was equivalent to another tree. It was pretty clear from the tone of the conversation that he was going to be a thumbs down.
In any event, I didn't go to Seattle expecting an offer and sure enough, the H.R. bot lady called two days after the interview to say "we've decided to go forward with another candidate". But like the Olympics, I am honored just to do these interviews and consider these fly-outs as an opportunity for me to exercise my (apparently out of shape) general comp sci technical muscles. Almost everyone I spoke with at the technical level was very recently out of school, so it may be that Amazon only prefers candidates who are book smart and not necessarily engineers who have built a portfolio of successful & shipping products. If you score an interview at Amazon, pat yourself on the back because at least you get to compete. Don't go in expecting to actually win a prize.